ijvp

Indian Journal of Veterinary Pathology

0250-47580973-970X

Indian Association of Veterinary Pathologists

ijvp-35-1-abs002

ABSTRACTS OF DISSERTATIONS OR ARTICLES

Epidemiology and pathology of ovine paratuberculosis at organised farms.

Sonawane

G.G.

¹Tripathi

N. B.

Dr.¹

¹Degree/year: Ph.D./2009, Name of the University: Deemed University, IVRI, Izatnagar

162011

351113113

2011

IndianJournals.com

Tissue samples were collected from 56 sheep. These animals were further classified as paucibacillary (PB) or multibacillary (MB) on the basis of histopathological findings and mycobacterial loads. Microscopically, small intestinal mucosa was predominantly infiltrated with large number of lymphocytes amid focal to multifocal granulomas observed in the basal lamina propria and ileal and jejunal Peyer's patches. Multinucleated giant cells were detected in the small intestines and MLN of a few cases. Focal to multiple small granulomas containing macrophages in the paracortical areas of the MLN were observed in most sheep. Acid-fast organisms were demonstrated in about 60% paucibacillary sheep. Among 38 multibacillary sheep, 22 were emaciated with moderate to severe weight loss diarrhea/soft faeces, wool shedding and occasional submandibular oedema. Microscopically, lesions were characterized by diffuse infiltration of epithelioid macrophages loaded with clusters of AFB many a times in sheet form, in flat, fused and club shaped villi with occasional giant cell formation (4 cases). Lesions were also evident in other layers of the intestines. Multiple macrophage granulomas with occasional presence of giant cells were observed in the paracortical and interfollicular areas of MLN/ICLN in 33 (86.8%) sheep. AFB were observed in all of the animals. Multifocal small granulomas consisting of lymphocytes and macrophages were observed in the liver in Merino (MB) (47.3%) and PB (16.6%) sheep without demonstration of AFB.

In PB sheep, IPT and ZN staining were found positive in 7(87.5%) and 4 (50%) cases respectively. In MB sheep, IPT and ZN had equal sensitivity. Out of 34 MB sheep, MAP were isolated on HEYM in 14 (41.2%) sheep, where as all PB sheep were negative. Among 38 sheep, IS900 PCR detected 21(55.2%), 251 PCR detected 25 (65.7%) and QRT-PCR detected all 23 (100%) sheep positive for MAP infection. The QRT-PCR results were significantly higher in detection of MAP genome in comparison to both PCR targeting IS900 and 251 genes. In PB sheep, CD4+ and IFN-γ labeled cells were significantly increased whereas in MB sheep, lower density of CD4+ cells and higher density of CD8+ cells were observed in the small intestine and MLN. PB sheep exhibited significantly increased expression of IFN-γ and iNOS, whereas MB sheep exhibited significantly decreased expression of these cytokines. Small intestine and MLN of the PB and MB sheep showed significantly high expression of IL-10 and TGF-β than in the tissues of uninfected sheep. No significant difference was found in the expression values of IL-10 and TGF-β between paucibacillary and multibacillary cases. The expression levels of IL-10 in the intestines of pauci- and multibacillary sheep were comparable but were significantly reduced in comparison to uninfected sheep. The expression levels of TRAF-1 were non-significantly increased in the small intestine of PB and MB sheep. Of the three farms of different breeds studied, the highest seroprevalence was found in the Chokla breed (13.1%), followed by Avikalin (7.70%) and Bharat Merino (6.3%) with overall prevalence of paratuberculosis (10.3%) at CSWRI, Avikanagar. Seroprevalence of MAP infection in unorganised farms of Rajasthan was found to be 1.5%. The indigenous ELISA compared well with the commercial Pourquire ELISA. The sensitivity and specificity of the ELISA were found to be 87.4% and 97.2% respectively, with accuracy of over 94%. On the basis of Kappa statistics, the assay was found to be in very good agreement with Pourquire ELISA. Sixty MAP isolates were analysed by IS1311 PCR-restriction endonuclease analysis. All but one Indian MAP strain were bison type whereas all UK strains were cattle type. The 25 isolates from various parts of UK recovered from cattle, sheep, goats, cows, badger, deer, mouflon, rat, rook and stoat were identified as cattle type.